1. Field of the Invention
The present invention relates generally to an apparatus for opening the doors of a railroad hopper car, and, in particular, to a novel apparatus for manually opening the hopper doors on a railroad car.
2. Description of the Prior Art
A common type of railroad freight car in use today is the freight car of the type wherein the load is discharged through hoppers in the underside of the body. Such cars are generally referred to as hopper cars and are used to haul coal, phosphate and other commodities.
After hopper cars are spotted over an unloading pit the doors of the hoppers are opened, allowing the material within the hopper to be emptied into the pit.
Hopper cars, which may be covered, are usually found with one of two hopper configurations: transverse, in which the doors closing the hoppers are oriented perpendicular to the center line of the car; or longitudinal, in which the doors closing the hoppers are oriented parallel to the center line of the car. An example of a hopper car with transverse doors is shown in U.S. Pat. No. 5,249,531, while an example of a hopper car with longitudinal doors is shown in U.S. Pat. No. 4,224,877.
Prior art references which teach operating mechanisms for opening and closing hopper doors include U.S. Pat. Nos. 3,596,609; 4,741,274; 3,187,684; 3,611,947; 3,786,764; 3,815,514; 3,818,842; 3,949,681; 4,222,334; 4,366,757; 4,601,244; 5,823,118; and 5,249,531. There are several disadvantages to the hopper door operating mechanisms described in some of the aforementioned patents. One problem is that some of the prior art mechanisms are designed such that each actuating mechanism is connected to doors from two separate hoppers. Thus, if the mechanism fails, it effects the operation of two hoppers. Another disadvantage of some of the above described hopper door mechanisms is that the operating mechanisms limit the distance of the door motion, thus limiting the open area of the cars bottom. This arrangement slows the unloading process and causes additional costs and potential damage to the car due to increased periods in thaw sheds. A further disadvantage of some of the prior art hopper door mechanisms are that they are designed specifically for new railcar construction.
U.S. Pat. No. 6,405,158 is directed to a manual discharge door operating system for a hopper railcar. It includes a door actuation shaft coupled to the railcar extending across the width of the car. Rotation of the actuation shaft by the operator opens and closes the discharge door of the hopper railcar through linkage assemblies which are affixed to the center sill of the car. The linkage assemblies form an over-center latch to aid in maintaining the door in the closed position.
While the mechanism taught in the '658 patent works well, it must be mounted to the center sill of the railcar. In addition, it is designed to operate a door of a hopper chute having a certain fixed slope angle.